<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var s=[
        [['a','b'],'c'],
       [ '2','5'],
        '3'
    ];

        console.log(s[0][0][1]+s[1][1]+3)
</script>

</body>
</html>